The present invention relates to building electrical system monitoring and control.
U.S. Patent Application Publication US 2007/0155349 (Nelson et al.) discloses a system for selectively controlling electrical outlets using power profiling. An electrical outlet includes a socket for receiving a plug, an outlet identification and a signal detector for detecting a signal from the plug, for sending the signal and outlet identification to a controller, and for receiving a command from the controller, such as to reduce or cut power to the device plugged into the outlet when the device's operation deviates from an operational profile for the device. The system may be used with motion sensors and other environmental components.
Blemel and Furse, “Applications of Microsystems and Signal Processing for Wiring Integrity Monitoring”, 2001 IEEE Aerospace Symposium, 12 pages, the disclosure of which is hereby incorporated by reference, discuss detection and prevention of wiring related problems in aerospace vehicles. Blemel presents a system in which sensors in an aircraft interface with processors; the processors are networked together on an aircraft and are able to communicate with a central web server. The processors implement algorithms for fault detection, identification, location, prediction and messaging.
U.S. Pat. No. 5,991,327 (Kojori) discloses a controller that receives a plurality of sensor readings, including some extra readings for diagnostic protection, and processes the readings to predict and control voltages and currents in an electric arc furnace.
An arc fault circuit interrupter (AFCI) is a circuit breaker designed to prevent fires by detecting non-working electrical arcs and disconnect power before the arc starts a fire. Arc faults in a home are one of the leading causes for household fires. AFCIs resemble a GFCI/RCD (Ground-Fault Circuit Interrupt/Residual-Current Device) in that they both have a test button. GFCIs are designed to protect against electrical shock, while AFCIs are primarily designed to protect against fire.
Starting with the 1999 version of the National Electrical Code (NEC, also called NFPA 70) in the United States, AFCIs are required in all circuits that feed receptacles in bedrooms of dwelling units. This requirement is typically accomplished by using a kind of circuit-breaker (defined by UL 1699) in the breaker panel that provides combined arc-fault and overcurrent protection. Not all U.S.A. jurisdictions have adopted the AFCI requirements of the NEC as written. An AFCI detects sudden bursts of electrical current in milliseconds, long before a standard circuit breaker or fuse would trip.
In 2002, the NEC removed the word “receptacle” leaving “outlets”, in effect adding lights within dwelling bedrooms to the requirement. The 2005 code made it more clear that all outlets must be protected. “Outlets” is defined in “Article 100 Definitions” of the NEC as “A point on the wiring system where current is taken to supply utilization equipment” and this includes receptacles, light fixtures, and smoke alarms, among other things.
Beginning January 2008, only “combination type” AFCIs will meet the NEC requirement. The 2008 NEC requires installation of combination-type AFCIs in all 15 and 20 amp residential circuits with the exception of laundries, kitchens, bathrooms, and garage, and unfinished basements.
Zigbee is a wireless technology that does not have the speed or bandwidth of Wi-Fi or Bluetooth, but is designed for wireless building controls. ZigBee is based on IEEE Standard 802.15.4 and creates a self-organizing wireless network where any ZigBee-compliant device introduced into the environment is automatically incorporated into the network as a node. A number of manufacturers are currently developing devices that incorporate this technology, including switches, thermostats and other common monitoring and control devices. ZigBee devices are battery powered, which means that they do not need any interconnecting wiring. These devices remain dormant until they are activated by an incoming signal, so their batteries can last for months or even years without replacement.
ZigBee devices have the ability to form a mesh network between nodes. Meshing is a type of daisy chaining from one device to another. This technique allows the short range of an individual node to be expanded and multiplied, covering a much larger area. One ZigBee network can contain more than 65,000 nodes (active devices). The network they form in cooperation with each other may take the shape of a star, a branching tree or a net (mesh). There are three categories of ZigBee devices: ZigBee Network Coordinator. Smart node that automatically initiates the formation of the network. ZigBee Router. Another smart node that links groups together and provides multi-hopping for messages. It associates with other routers and end-devices. ZigBee End Devices. Sensors, actuators, monitors, switches, dimmers and other controllers.
Z-Wave is an interoperable standard for residential and light commercial devices, providing reliable, confirmable, low bandwidth, half duplex two way control communications via wireless mesh neworking. The Z-Wave development platform is described at www.zen-sys.com. The Z-Wave Protocol is for communicating short control messages from a control unit to one or more slave units. Slave units can forward commands to other slave units. The ZM3102N Z-Wave Module contains the ZW0301 Z-Wave Single Chip, system crystal and RF front-end circuitry. The ZW0301 Single Chip includes an RF transceiver, 8051 MCU core, SRAM, Flash Memory for Z-Wave Protocol and OEM Application storage software, Triac Controller, and various hardware interfaces.
Motorola sells Home Monitoring and Control System Wireless Temperature Sensors, namely model HMTS1050 and model HMSM4150, that are intended to be placed in a room, and programmed with an upper and/or lower limit. When the limit is exceeded, the system sends a text alert to a cell phone or e-mail.
While there is concern about the electrical infrastructure of buildings, including residential and commercial, there is still room for improvement.